Abstract: Argumentation techniques have been widely concerned by AI researchers in recent years．How to construct qualified counter-arguments efficiently for the argumentation process still remains to be a difficult problem．The nature of arguments was analyzed,and concepts relating to arguments and relations between these concepts were formally defined,and the knowledge representation of arguments was structured．Then an argument ontology was implemented．An instance of an argumentation process was used to testify consistency and usability of the argument ontology.In a prototype system built on this ontology,arguments needed in argumentation processes can be aquired by quering or constructing based on the ontology．Arguments constructed previously are reused,thus the computing efficiency of automatic argumentation is enhanced．

Key words: Argumentation,Argument,Knowledge representation,Ontology